1. Field of the Invention
The present invention generally relates to a method for detecting tilt of an optical pickup head.
2. Description of Related Art
In recent years, optical disk recording and/or reproducing devices have been widely used as portable storing and reproducing electronic consuming devices in our daily life. Each optical disk recording and/or reproducing device mainly includes an optical pickup head for emitting a light beam, a guiding apparatus for movably supporting the optical pickup head, and a driving mechanic for driving the optical pickup head to move.
Referring to FIG. 8, an optical disk recording and/or reproducing device 10 is used for recording data to and/or reproducing data from an optical disk 150. In the optical disk recording and/or reproducing device 10, an optical pickup head 120 is movably supported in two guiding poles 106, and a stepping motor 108 is used for moving the optical pickup head 120 along the guiding poles 106. When the guiding poles 106 are not parallel to each other, a tilt occurs. If the guiding poles 106 are parallel to each other, but the virtual plane defined by the guiding poles 106 is not parallel to the turntable 104, the tilt is also generated. When the optical pickup head 120 is tilted, light from the optical pickup head 120 cannot be vertically projected to the optical disk 150. The tilt of the optical pickup head 120 is a main factor influencing recording and reproducing capability of the optical disk recording and/or reproducing device 10.
Therefore, it is important to detect the tilt of the optical pickup head 120. Referring to FIGS. 9, 10, a conventional method is used to detect the tilt using a collimator 200 and three reflecting planes 132, 134, 136. The reflecting planes 132, 134, 136 are set on the turntable 104, and two ends of the guiding poles 106 respectively. In operation, the collimator 200 emits light beams, and the light beams are projected to the reflecting planes 132, 134, 136 and reflected therefrom. The reflected light beam are received and analyzed by the collimator 200, and information carried in the reflected light beams is displayed on a display screen (not shown). Referring also to FIG. 11, three light spots 42, 44, 46 are displayed in an image 40. Herein, the light spots 42, 44 are formed by the light beams reflected from the reflecting planes 134, 136, which are defined as static spots. The light spot 46 is formed by the light beam reflected from the reflecting plane 132, which is defined as dynamic spot.
If the static spots 42, 44 are both laid on center of the dynamic spot 46, it is determined that no tilt is generated. If one of the static spots departs from the center of the dynamic spot 46, a first distance between the center of the departure static spot and the center of the dynamic spot represents a first unparallel degree of the guiding poles 106 to the turntable 104, and a second distance between the center of the static spot 42 and the center of the static spot 44 represents a second unparallel degree of the guiding poles 106. If the static spots both depart from the center of the dynamic spot 46, a bigger distance between the center of the dynamic spot 46 and the centers of the static spots 42, 44 represents the first unparallel degree. Herein, the center means a geometric center of a minimum virtual rectangle that can enclose a spot.
In practice, the first and the second distances are measured manually to determine the tilt. Therefore, the conventional method includes some deficiencies, such as man-made determination error and low work efficiency.
Therefore, improvements for a tilt detecting method are needed in the industry to address the aforementioned deficiency.